1. Field of the Invention
The invention relates to a circuit arrangement for the summation of products formed by analog signals and digital coefficients in which the products are produced with the use of a multiplying digital-analog converter.
2. Description of the Prior Art
Circuit arrangements are already known with the aid of which the sum of products are produced for analog signals and coefficients illustrated in an analog manner and assigned to said products. Such a circuit arrangement, for example, is disclosed in German Auslegeschrift No. 1,157,677 in conjunction with a digital filter. In this known circuit arrangement, analog signals which are emitted at the outputs of transit time elements are multiplied with the aid of potentiometers having analogously adjustable coefficients. The signals relating to the product of the analog signals and the coefficients are fed to a summation stage. The summation stage emits a signal at its output which is proportional to the sum formed by the analog signals and the respectively assigned coefficients. It is also conceivable to employ analog multiplier stages instead of the potentiometers. However, the circuit arrangement operates in both cases without sufficient precision as the coefficients have to be respectively analogously adjusted.
It would also be conceivable to provide digital multiplier stages instead of the analog multiplier stages and to also provide a digital summation stage instead of the analog summation stage. The digital multiplication and summation can be accomplished with great precision, however, such a circuit arrangement would be very expensive. Moreover, analog-digital converters would be required at the outputs of the transit time elements in order to assign digital values to the analog signals.